Progesterone concentrations during estrous cycle of dairy cows exposed to electric and magnetic field

Department of Animal Science, McGill University, Sainte Anne de Bellevue, QC, Canada.
Bioelectromagnetics (Impact Factor: 1.71). 02/1998; 19(7):438-43. DOI: 10.1002/(SICI)1521-186X(1998)19:73.0.CO;2-2
Source: PubMed


Sixteen multiparous nonpregnant lactating Holstein cows (each weighing 662 +/- 65 kg in 150.4 +/- 40 day of lactation) were confined to wooden metabolic cages with 12:12 h light:dark cycle during the experiment. The cows were divided into two sequences of eight cows each and exposed to electric and magnetic fields (EMF) in an exposure chamber. This chamber produced a vertical electric field of 10 kV/m and a uniform horizontal magnetic field of 30 microT at 60 Hz. One sequence was exposed for three estrous cycles of 24 to 27 days. During the first estrous cycle, the electric and magnetic fields were off; during the second estrous cycle, they were on; and during the third estrous cycle, they were off. The second sequence was also exposed for three 24 to 26 days estrous cycles, but the exposure to the fields was reversed (first estrous cycle, on; second estrous cycle, off; third estrous cycle, on). The length of each exposure period (21 to 27 days) varied according to the estrous cycle length. No differences were detected in plasma progesterone concentrations and area under the progesterone curve during estrous cycles between EMF nonexposed and exposed periods (2.28 +/- 0.17 and 2.25 +/- 0.17; and 24.5 +/- 1.9 vs. 26.4 +/- 1.9 ng/ml, respectively). However, estrous cycle length, determined by the presence of a functional corpus luteum detected by concentrations of progesterone equal to or more than 1 ng/ml plasma, was shorter in nonexposed cows than when they were exposed to EMF (22.0 +/- 0.9 vs. 25.3 +/- 1.4 days).

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    • "In addition, EMFs created by power lines (the highest EMFs that are likely to be encountered by people; WHO, 2002) may differ in intensity between different continents and countries; for example, many power lines in North America carry high voltage direct current (DC) while low voltage alternating current (AC) is used in Europe. Overall, experimental data have shown that EMFs can affect a wide range of biological processes (reviewed in Fernie and Reynolds, 2005), including reproduction (e.g., Burchard et al., 1998; Al-Akhras et al., 2001; Rodriguez et al., 2003), growth (e.g., Tsoneva et al., 1975; Rodriguez et al., 2002) and development (e.g., Youbicier-Simo et al., 1997; Stamenkovic´-Radak et al., 2001; reviewed by Juutilainen, 2005). Experiments aimed at searching for biological effects of EMFs have been mostly carried out in vitro "
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    ABSTRACT: Exposure to electromagnetic fields (EMFs) can affect a wide range of biological processes, including reproduction, growth and development. Experiments aimed at investigating the biological effects of EMFs, focused on potential harmful effects on humans, have been mostly carried out in vitro or with animal models in laboratory conditions. By contrast, studies performed on wild animals are scarce. The effects of EMFs created by an electric power line on reproductive traits of a wild great tit (Parus major) population were explored by analysing data gathered during nine breeding seasons. EMF exposure significantly increased clutch size (7%) and egg volume (3%), implying a 10% increase in clutch volume. This indicates an increase in reproductive investment from parent birds exposed to EMFs as compared to the adjacent reference area. These results cannot be attributed to habitat or adult quality differences between the exposed and reference group. Nevertheless, no differences in hatching success or final productivity (fledging and reproductive success or nestling body mass) could be detected. Our study clearly shows that EMFs created by power lines can have biological consequences in wild organisms that live intimately with them. To our knowledge, this is the first study showing an increase in clutch size, and one of the few reporting an increase in egg size, associated with EMF exposure. The possible mechanisms by which great tits invest more under EMF exposure are discussed, and future research directions to evaluate the effect of EMFs on avian reproduction in the wild are suggested.
    Environmental Research 08/2012; 118:40-6. DOI:10.1016/j.envres.2012.07.007 · 4.37 Impact Factor
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    • "Eventually, this can alter the production of gonadal sex steroids, resulting in changes in the reproductive cycle [39,40]. In cows, exposure to 60 Hz SLF-EMF at 30 µT for 24-27 days did not alter the progesterone levels but shortened the estrous stage [41]. RF-EMF exposure can affect ACTH, GH, TSH, FSH, and LH in the pituitary [42]. "
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    ABSTRACT: The safety of human exposure to an ever-increasing number and diversity of electromagnetic field (EMF) sources both at work and at home has become a public health issue. To date, many in vivo and in vitro studies have revealed that EMF exposure can alter cellular homeostasis, endocrine function, reproductive function, and fetal development in animal systems. Reproductive parameters reported to be altered by EMF exposure include male germ cell death, the estrous cycle, reproductive endocrine hormones, reproductive organ weights, sperm motility, early embryonic development, and pregnancy success. At the cellular level, an increase in free radicals and [Ca(2+)]i may mediate the effect of EMFs and lead to cell growth inhibition, protein misfolding, and DNA breaks. The effect of EMF exposure on reproductive function differs according to frequency and wave, strength (energy), and duration of exposure. In the present review, the effects of EMFs on reproductive function are summarized according to the types of EMF, wave type, strength, and duration of exposure at cellular and organism levels.
    Clinical and Experimental Reproductive Medicine 03/2012; 39(1):1-9. DOI:10.5653/cerm.2012.39.1.1
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    • "Regarding the endocrine system, besides pineal studies, the sensitivity of pituitary gland, adrenal gland and thyroid gland to electromagnetic field (EMF) influence was investigated too, as well as of the endocrine pancreas, testicles and ovaries (Ossenkopp et al., 1972; Zagorskaya, 1989; Picazo et al., 1995; Zagorskaya et al., 1990; Forgacs et al., 1998; Burchard et al., 1998; Feria-Velasko et al., 1998; Uscebrka et al., 1999; Matavulj et al., 2000). Our previous investigations of ELF-EMF influence on thyroid gland have shown that in toto exposure of rats to these fields alters thyroid activity (Matavulj et al., 1996). "
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    ABSTRACT: Objective of our study was to use morphophysiological criteria in order to determine the sensitivity of male rat thyroid gland to an extremely low frequency electromagnetic field (ELF-EMF) influence and the ability of the gland to repair after period of exposure. Animals were exposed to 50Hz, 50-500 microT ELF-EMF for 3 months when a part of them (group I) were sacrificed, while the rest of animals were subjected to recovery evaluation of the gland and sacrificed after 1 (group II), 2 (group III) and 3 (group IV) weeks. Histological and stereological analyses were performed on paraffin and semifine thyroid gland sections. Serum T3 and T4 were also determined. Histological and stereological analyses showed that the volume density of follicular epithelium and thyroid activation index decreased, while the volume density of colloid and capillary network increased in group I, II and III. The values of all these parameters in group IV were similar to corresponding controls. Serum T3 and T4 concentrations were significantly lower in all exposed animals, except in group I. Results of this study demonstrate that after significant morphophysiological changes caused by ELF-EMF exposure thyroid gland recovered morphologically, but not physiologically, during the investigated repair period.
    Tissue and Cell 07/2003; 35(3):223-31. DOI:10.1016/S0040-8166(03)00029-6 · 1.25 Impact Factor
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